It certainly ignores a lot of human productivity studies that indicate people rarely work at full manual labor productivity past 8 hours and full creative work productivity (including problem solving and often socialization skills) past 4 hours.
It certainly may be the case that they actually are interested in seeing interviewees past such points in a somewhat controlled environment.
Such "gauntlet" interviews seem common among large technology companies and while I think some of it is a semi-intentional attempt to push interviewers to limits to see how they react, I think it's also just as much "everybody else does it" and that continual momentum of existing interview processes. Which is precisely how such hazing processes in organizations get normalized and their problems ignored over the long term. (Yes, pushing someone to the limits of their productivity is strenuous activity and the very definition of hazing.)
I wouldn't worry about the BS interview. I would imagine at some point they'll talk about thing things you've accomplished and it's important to show confidence and get through the parts of interview you know don't matter that much. If they hire some kid out of college versus someone with experience who tells them they can get up to speed quickly and do the job. Good luck too them. If someone does well on both more power to them, but unlikely. I kept pointing out I could look it up on the internet in 2 seconds.
This seems like they're selecting for candidiates that will tolerate a job that is perpetual crunch-time.
May be ask them to split interview into two days. I have done it before and I don't think it negatively impacted anything.
It seems they are looking for candidates who can work for long hours and under pressure.
Cynical alternative: The job is meant exclusively for H1B candidates, and the posting is just so they can say they had no qualified locals.